docs(tools): qualify the three remaining mode-dependent only-claims

The `mode: 'code'` qualification landed on the module header and
`isBareIdentifier` but not on the other three sites the same reviews
enumerated. `UNPRINTABLE`'s "only declaration of the tools", the open-object
comment's "only signal that extra keys are accepted", and the docstring
comment's "only description of what a tool does" are each false under
`mode: 'both'`, where the native schemas ship alongside the SDK.

Widen the note's predicate-path sentence past head and last position: a
character added to `XID_Continue` passes `IDENTIFIER`'s trailing quantifier
anywhere after the head, the middle of a name included.

Record the ƛ test's table provenance. U+A7DC and the U+019B mapping to it
both arrive in Unicode 16.0, and the engines floor sits exactly there:
Node 22.19.0 reports Unicode 16.0 (ICU 77.1) and produces the mapping.

packages/core/tools/src/py-types.ts

@@ -155,8 +155,8 @@ interface RenderState {
  * CPython rejects source containing a NUL outright
  * (`SyntaxError: source code string cannot contain null bytes`), whether it
  * sits in a docstring or in a comment, so one such byte anywhere in a schema
- * description would make the whole generated SDK unparseable — the model's only
- * declaration of the tools. The rest are legal but invisible; escaping them
+ * description would make the whole generated SDK unparseable — under
+ * `mode: 'code'`, the model's only declaration of the tools. The rest are legal but invisible; escaping them
  * with the same rule keeps the emitted text readable and the treatment uniform.
  *
  * The boundary is the category, not per-code-point addressability: `\xNN`
@@ -557,9 +557,9 @@ function renderType(schema: unknown, className: string, state: RenderState): str
           }
         }
         // TypedDict syntax cannot express openness, so an open object states it
-        // in-band: the annotation is advisory either way, and Code Mode omits
-        // the native schemas, making this line the model's only signal that
-        // extra keys are accepted.
+        // in-band: the annotation is advisory either way, and `mode: 'code'`
+        // omits the native schemas, making this line the model's only signal
+        // that extra keys are accepted.
         if (node.additionalProperties !== false) {
           lines.push(`${pad(1)}# Additional keys beyond those declared are allowed.`)
         }
@@ -753,9 +753,9 @@ export function renderToolsSdkPy(schemas: ToolSdkSchema[]): string {
       // of that method's body. Emitted before the `async def` it would instead
       // become the `Tools` class docstring (for the first tool) or a dead
       // expression (for every later one), leaving every method undocumented —
-      // and this SDK is the model's only description of what a tool does. A
-      // docstring is a complete body, so the `...` stub is only for the
-      // description-less case.
+      // and under `mode: 'code'` this SDK is the model's only description of
+      // what a tool does. A docstring is a complete body, so the `...` stub is
+      // only for the description-less case.
       const doc = docLines(schema.description, 2)
       members.push(doc.length > 0
         ? `${pad(1)}async def ${schema.name}(self, args: ${argType}) -> ${outputType}:`

packages/core/tools/tests/py-types.spec.ts

@@ -480,6 +480,14 @@ describe('renderToolsSdkPy', () => {
     // an older interpreter's do not. This pins which table produced the name,
     // so a change to the mapping step shows up here rather than only in a
     // downstream Python parse.
+    //
+    // Unlike the other Unicode cases in this file, the table row is recent:
+    // U+A7DC and the U+019B uppercase mapping to it both arrive in Unicode
+    // 16.0 (`DerivedAge.txt`; CPython 3.12.13's 15.0.0 has neither). The
+    // engines floor sits exactly there with no margin — Node 22.19.0 reports
+    // Unicode 16.0 (ICU 77.1) and maps U+019B to U+A7DC, measured — so an
+    // engine below the floor fails here as a renderer regression whose real
+    // cause is the table version.
     const text = renderToolsSdkPy([
       {
         name: 'ƛ',